Navigation device

ABSTRACT

Disclosed is a navigation device which extracts an entrance and exit section which exists ahead of a vehicle and in which a vehicle is permitted to make a lane change between an HOV lane and a normal lane on the basis of information about the position of the vehicle and map data in which the HOV lane and the normal lane are defined by a single link, extracts a branch point on the HOV lane existing ahead of the vehicle on the basis of the map data and the position information, determines a guidance time for the extracted entrance and exit section, and another guidance time for the branch point, and provides guidance notifying that the vehicle can exit the HOV lane or guidance notifying that the vehicle can enter the HOV lane at the guidance time, or provides guidance on the branch at the other guidance time.

FIELD OF THE INVENTION

The present invention relates to a vehicle-mounted navigation device forproviding route guidance. More particularly, it relates to a techniqueof providing information related to HOV (High Occupancy Vehicle) lanes.

BACKGROUND OF THE INVENTION

Conventionally, an HOV lane or the like which is used in a road systemmainly seen in, for example, a North American big city is known as aroad on which restrictions showing which vehicles can enter the road areimposed. An HOV lane is also called a car pool lane and is a lane inwhich only vehicles with two or more people are allowed to travel. Alane disposed along with normal lanes on a highway, a lane which is ashortcut of an interchange, etc. are known as HOV lanes. A road systemwhich adopts such an HOV lane provides the user with a preferentialtreatment that makes it possible to arrive at his or her destination ina shorter time as long as the user travels in an HOV lane so as to prodthe user to share the vehicle with one or more other persons, therebyreducing the traffic as a whole and therefore reducing traffic jams.

As a technique related to such an HOV lane, patent reference 1 disclosesa navigation device which searches for a route by using, informationabout HOV lanes as road information about a route leading to adestination set up by the user. In this navigation device, map dataincluding road information about entrance and exit points in a highwayhaving an HOV lane are read from a DVD and are stored in a data bufferin order to enable the user to efficiently travel in a lane on whichrestrictions against lane changes for entrance into and exit fromanother lane are imposed. A route search processing unit carries out aroute search process in consideration of the enable or disable of use ofan HOV lane by using the map data stored in the data buffer. Whenproviding route guidance using an HOV lane, an HOV lane guidance unitprovides guidance on a certain lane change with an image and a voice atthe time that an entrance or exit point at which the user's vehicleshould change its traveling direction falls within a predetermineddistance from the position of the vehicle.

RELATED ART DOCUMENT Patent reference

-   Patent reference 1: Japanese Unexamined Patent Application    Publication No. 2001-183159

A problem is, however, that when providing guidance by using map data inwhich an HOV lane and a normal lane (a lane other than HOV lanes) areexpressed by a single link, an appropriate guidance time, a guidancedescription, or the like for such a road cannot be presented.

The present invention is made in order to solve the problem, and it istherefore an object of the present invention to provide a navigationdevice which can provide appropriate guidance for the user all the timeuntil the user reaches his or her destination even in a case of usingmap data in which an HOV lane and a normal lane are expressed by asingle link.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a navigationdevice including: a map data acquiring unit for acquiring map data inwhich a road in which entrance and exit between a special lane which isa part of a plurality of lanes and a normal lane which is a remainingone of the plurality of lanes are permitted only in a predeterminedpermitted section is defined by a single link; an entrance and exitextracting unit for extracting an entrance and exit section which existsahead of a vehicle and in which the vehicle is permitted to make a lanechange between a special lane and a normal lane on a basis of the mapdata acquired by the map data acquiring unit and position informationabout the vehicle; a branch extracting unit for extracting a branchpoint on a special lane which exists ahead of the vehicle on a basis ofthe map data acquired by the map data acquiring unit and the positioninformation about the vehicle; a guidance time adjusting unit fordetermining a guidance time for a start point of a lane changingpermitted section defined by the entrance and exit section extracted bythe entrance and exit extracting unit, and another guidance time for thebranch point extracted by the branch extracting unit; and a control unitfor providing exit guidance notifying that the vehicle is permitted toexit the special lane or entrance guidance notifying that the vehicle ispermitted to enter the special lane at the guidance time determined bythe guidance time adjusting unit, or branch guidance on the branch pointon the special lane at the other guidance time determined by theguidance time adjusting unit.

In accordance with the present invention, there is provided a navigationdevice comprising: a map data acquiring unit for acquiring map data inwhich a road in which entrance and exit between a special lane which isa part of a plurality of lanes and a normal lane which is a remainingone of the plurality of lanes are permitted only in a predeterminedpermitted section is defined by a single link; an entrance and exitextracting unit for extracting an entrance and exit section which existsahead of a vehicle and in which the vehicle is permitted to make a lanechange between a special lane and a normal lane on a basis of the mapdata acquired by the map data acquiring unit and position informationabout the vehicle; a branch extracting unit for extracting a branchpoint on a special lane which exists ahead of the vehicle on a basis ofthe map data acquired by the map data acquiring unit and the positioninformation about the vehicle; a guidance time adjusting unit fordetermining a point which is determined on a basis of a length of a lanechanging permitted section defined by the entrance and exit sectionextracted by the entrance and exit extracting unit as a guidance timefor the lane changing permitted section, and determining the guidancetime in such a way that the guidance time varies depending on whetherthe lane changing permitted section has a predetermined length orgreater, or a plurality of lane changing permitted sections exist over adistance equal to the predetermined length; and a control unit forproviding exit guidance notifying that the vehicle is permitted to exitthe special lane or entrance guidance notifying that the vehicle ispermitted to enter the special lane, or branch guidance on the branchpoint on the special lane at the guidance time determined by theguidance time adjusting unit.

In accordance with the present invention, there is provided a navigationdevice comprising: a map data acquiring unit for acquiring map data inwhich a road in which entrance and exit between a special lane which isa part of a plurality of lanes and a normal lane which is a remainingone of the plurality of lanes are permitted only in a predeterminedpermitted section is defined by a single link; an entrance and exitextracting unit for extracting an entrance and exit section which existsahead of a vehicle and in which the vehicle is permitted to make a lanechange between a special lane and a normal lane on a basis of the mapdata acquired by the map data acquiring unit and position informationabout the vehicle; a branch extracting unit for extracting a branchpoint on a special lane which exists ahead of the vehicle on a basis ofthe map data acquired by the map data acquiring unit and the positioninformation about the vehicle; a guidance time adjusting unit fordetermining a guidance time for a lane changing permitted sectiondefined by the entrance and exit section extracted by the entrance andexit extracting unit, and another guidance time for the branch pointextracted by the branch extracting unit, the guidance time adjustingunit changing the guidance times according to whether a lane in whichthe vehicle is traveling is the special lane or the normal lane; and acontrol unit for providing exit guidance notifying that the vehicle ispermitted to exit the special lane or entrance guidance notifying thatthe vehicle is permitted to enter the special lane at the guidance timechanged, or branch guidance on the branch point on the special lane atthe other guidance time changed.

In accordance with the present invention, there is provided a navigationdevice comprising: a map data acquiring unit for acquiring map data inwhich a road in which entrance and exit between a special lane which isa part of a plurality of lanes and a normal lane which is a remainingone of the plurality of lanes are permitted only in a predeterminedpermitted section is defined by a single link; an entrance and exitextracting unit for extracting an entrance and exit section which existsahead of a vehicle and in which the vehicle is permitted to make a lanechange between a special lane and a normal lane on a basis of the mapdata acquired by the map data acquiring unit and position informationabout the vehicle; a branch extracting unit for extracting a branchpoint on a special lane which exists ahead of the vehicle on a basis ofthe map data acquired by the map data acquiring unit and the positioninformation about the vehicle; a forwardly-existing sign detecting unitfor detecting a sign related to a special lane existing forwardly; aguidance time adjusting unit for determining a guidance time for a lanechanging permitted section defined by the entrance and exit sectionextracted by the entrance and exit extracting unit, and another guidancetime for the branch point extracted by the branch extracting unitaccording to a position of the sign detected by the forwardly-existingsign detecting unit or a distance to an exit displayed on the sign; anda control unit for providing exit guidance notifying that the vehicle ispermitted to exit the special lane or entrance guidance notifying thatthe vehicle is permitted to enter the special lane at the guidance timedetermined by the guidance time adjusting unit, or branch guidance onthe branch point on the special lane at the other guidance timedetermined by the guidance time adjusting unit.

The navigation device in accordance with the present invention canprovide appropriate guidance for the user at an appropriate time all thetime until the user reaches his or her destination even in a case ofusing the map data in which an HOV lane and a normal lane are expressedby a single link.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing the hardware configuration of anavigation device in accordance with Embodiment 1 of the presentinvention;

FIG. 2 is a functional block diagram showing the functional structure ofa control unit which constructs the navigation device in accordance withEmbodiment 1 of the present invention;

FIG. 3 is a flowchart showing an operation of the navigation device inaccordance with Embodiment 1 of the present invention;

FIG. 4 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 2 of the present invention;

FIG. 5 is a view for explaining an operation of the navigation device inaccordance with Embodiment 2 of the present invention;

FIG. 6 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 3 of the present invention;

FIG. 7 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 4 of the present invention;

FIG. 8 is an explanatory drawing for explaining an operation ofproviding guidance with reference to a highway exit which is performedby the navigation device in accordance with Embodiment 4 of the presentinvention when the user exits an HOV lane;

FIG. 9 is an explanatory drawing for explaining an operation ofproviding guidance with reference to a highway entrance start pointwhich is performed by the navigation device in accordance withEmbodiment 4 of the present invention when the user enters an HOV lane;

FIG. 10 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 5 of the present invention;

FIG. 11 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 6 of the present invention;

FIG. 12 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 7 of the present invention;

FIG. 13 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 8 of the present invention;

FIG. 14 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 9 of the present invention;

FIG. 15 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 10 of the present invention;

FIG. 16 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 11 of the present invention;

FIG. 17 is a flow chart showing an operation of a navigation device inaccordance with a variant of Embodiment 11 of the present invention;

FIG. 18 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 12 of the present invention;

FIG. 19 is a flow chart showing an operation of a navigation device inaccordance with Embodiment 13 of the present invention;

FIG. 20 is a view showing a road image and a link image for explainingthe operation of the navigation device in accordance with Embodiment 13of the present invention;

FIG. 21 is a view showing destination sign information for explainingthe operation of the navigation device in accordance with Embodiment 13of the present invention;

FIG. 22 is a flow chart showing an operation when the user exits an HOVlane which is performed by a navigation device in accordance withEmbodiment 14 of the present invention; and

FIG. 23 is a flow chart showing an operation when the user enters an HOVlane which is performed by the navigation device in accordance withEmbodiment 14 of the present invention.

EMBODIMENTS OF THE INVENTION

Hereafter, the preferred embodiments of the present invention will beexplained in detail with reference to the drawings.

Embodiment 1.

A navigation device in accordance with Embodiment 1 of the presentinvention is constructed in such a way as to appropriately provideguidance at a time when a vehicle exits from an HOV lane by using mapdata in which an HOV lane and a normal lane are expressed by a singlelink. An HOV lane as mentioned above corresponds to a “special lane” inaccordance with the present invention. A special lane is not limited toan HOV lane, and can alternatively consist of another lane on whichrestrictions against lane changes for entrance into and exit from anormal lane are imposed.

FIG. 1 is a block diagram showing the hardware configuration of anavigation device in accordance with Embodiment 1 of the presentinvention. This navigation device is provided with an input unit 11, aGPS (Global Positioning System) receiver 12, a heading sensor 13, adistance sensor 14, a forwardly-existing sign detecting camera 15, a mapdata storage unit 16, a display unit 17, a sound output unit 18, and acontrol unit 19.

The input unit 11 can be comprised of, for example, a touch panel placedon the screen of the display unit 17. This input unit 11 is used inorder for a user to set a place of departure, a destination, a waypoint,or the like for a route search, and to provide one of various commandsto the navigation device. Information inputted from this input unit 11is sent to the control unit 19 as an operation signal.

The GPS receiver 12 detects the current position of a vehicle in whichthis navigation device is mounted on the basis of GPS signals receivedfrom GPS satellites not shown. The current position of the vehicledetected by this GPS receiver 12 is notified to the control unit 19 as acurrent position signal. The heading sensor 13 detects the headingtoward which the vehicle is headed, and notifies this heading to thecontrol unit 19 as a heading signal. The distance sensor 14 detects thetravel distance traveled by the vehicle, and notifies this traveldistance to the control unit 19 as a distance signal.

The forwardly-existing sign detecting camera 15 detects a sign on an HOVlane which exists ahead of the vehicle. The position of the sign and animage of the sign which are detected by this forwardly-existing signdetecting camera 15 (e.g. a character string or the like showing thedistance to an exit displayed on the sign) are notified to the controlunit 19 as a sign signal.

The map data storage unit 16 is comprised of, for example, an HDD (HardDisk Drive) device, and stores various types of data for implementing anavigation function as well as digitized map data including road dataabout roads each of which is defined by links and nodes. The map datastorage unit 16 is not limited to the HDD device, and can bealternatively comprised of a drive device for reading data from a DVD(Digital Versatile Disk) or a CD (Compact Disc) mounted thereto, a USBmemory, or an SD card.

Roads shown by the road data include a road which is defined by a singlelink, and in which the vehicle is permitted to enter and exit an HOVlane which is one of a plurality of lanes from and to a normal lanewhich is one of the remaining lanes only in a predetermined permittedsection. Link data showing links include HOV lane position informationshowing the positions of HOV lanes, HOV lane presence or absenceinformation showing whether or not an HOV lane is running parallel withother lanes in each road, lane changing permitted section informationshowing sections in each of which the vehicle is permitted to make alane change between an HOV lane and a normal lane, time regulationinformation showing whether or not the vehicle is permitted to passthrough the entrances and exits of each HOV lane according to time ofday, road names, and road numbers. The data stored in this map datastorage unit 16 can be read by the control unit 19.

The display unit 17 is comprised of, for example, an LCD (Liquid CrystalDisplay), and displays a map, a route, an enlarged map, various guidemessages, etc. on the screen thereof according to an image signal sentthereto from the control unit 19. The sound output unit 18 is comprisedof, for example, a speaker, and outputs a guidance message either for anexit from an HOV lane to a normal lane or an entrance into an HOV lanefrom a normal lane by voice according to a voice signal sent theretofrom the control unit 19.

The control unit 19 controls the whole of the navigation device, as willbe mentioned in detail below. This control unit 19 is provided with aCPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM(Random Access Memory) 23, a display control unit 24, and an input andoutput controller 25.

The CPU 21 uses the RAM 23 as a work memory, and operates according to aprogram read from the ROM 22 to perform one of the various processesincluding a route search and extraction of guidance points. The ROM 22stores programs and data which the CPU 21 reads to perform the variousprocesses. The RAM 23 is used as the work memory of the CPU 21, asmentioned above, and temporarily stores data being arithmetic-processed(e.g. expanded map data).

The display control unit 24 controls the display unit 17. Concretely,the display control unit 24 converts display data generated by the CPU21 into an image signal, and sends this image signal to the display unit17 via the input and output controller 25. The input and outputcontroller 25 functions as an interface between the control unit 19 andthe input unit 11, the GPS receiver 12, the heading sensor 13, thedistance sensor 14, the forwardly-existing sign detecting camera 15, themap data storage unit 16, the display unit 17, and the sound output unit18 which are connected to the control unit 19, and controls transmissionand reception of signals between the control unit and these components.

Next, the details of functions implemented by the control unit 19 willbe explained. FIG. 2 is a functional block diagram showing thefunctional configuration of the control unit 19. The control unit 19 isprovided with a control part 30, a map data acquiring unit 31, a currentposition detecting unit 32, a route searching unit 33, a route storageunit 34, an HOV lane determining unit 35, an HOV lane entrance and exitextracting unit 36, a passable or impassable determining unit 37, aforwardly-existing sign detecting unit 38, a guidance time adjustingunit 39, a display processing unit 40, a voice message generating unit41, a voice guidance unit 42, and a branch-on-HOV-lane extracting unit43. These components except the route storage unit 34 are implementedthrough program processes carried out by the CPU 21.

The control part 30 controls the whole of the control unit 19. Forexample, the control part 30 controls start and stop of each of thecomponents connected thereto, and transmission and reception of dataamong these components. The map data acquiring unit 31 acquires map datafrom the map data storage unit 16, and sends these map data to thecontrol part 30.

The current position detecting unit 32 detects the current position ofthe vehicle on the basis of both the current position signal sentthereto from the GPS receiver 12 or a current position signal which thecurrent position detecting unit generates with dead reckoning by usingthe heading signal sent thereto from the heading sensor 13 and thedistance signal sent thereto from the distance sensor 14, and the mapdata acquired from the map data acquiring unit 31 via the control part30. Because transmission and reception of data among the componentsconnected to the control part 30 are all carried out via the controlpart 30, a description of the process of carrying out transmission andreception of data via the control part 30 will be omitted hereafter insome cases.

Even though the vehicle is traveling a road expressed by a single linkon map data, the current position detecting unit 32 can detect in whichlane shown by the single link the vehicle is actually traveling. Thecurrent position of the vehicle detected by this current positiondetecting unit 32 is notified to the control part 30 as current positiondata.

The route searching unit 33 searches for a route from either the currentposition shown by the vehicle position information sent thereto from thecurrent position detecting unit 32 or the place of departure inputtedthereto from the input unit 11, to the destination inputted thereto fromthe input unit 11 on the basis of the map data acquired by the map dataacquiring unit 31. The route which this route searching unit 33 hassearched for is notified to the route storage unit 34 as route data.

The route storage unit 34 is disposed in, for example, a part of the RAM23 included in the control unit 19, and stores the route data sentthereto from the route searching unit 33. The route data stored in thisroute storage unit 34 can be read by the control part 30.

The HOV lane determining unit 35 determines whether or not an HOV laneis included in either the road included in the map data acquired by themap data acquiring unit 31 or the route shown by the route data storedin the route storage unit 34. The result of the determination acquiredby this HOV lane determining unit 35 is sent to the control part 30.

The HOV lane entrance and exit extracting unit 36 corresponds to an“entrance and exit extracting unit” in accordance with the presentinvention. When the result of the determination sent thereto via thecontrol part 30 from the HOV lane determining unit 35 shows that an HOVlane is included in the road or the route, the HOV lane entrance andexit extracting unit extracts an entrance and exit section in which thevehicle is permitted to make a lane change between a normal lane and theHOV lane. This entrance and exit section defines a lane changingpermitted section. The entrance and exit section extracted by this HOVlane entrance and exit extracting unit 36 is notified to the controlpart 30 as entrance and exit position data.

The passable or impassable determining unit 37 determines whether thevehicle can pass through the HOV lane in the road or the route which theHOV lane determining unit 35 has determined includes the HOV lane on thebasis of both the number of passengers shown by number-of-passengersdata sent thereto from a number-of-passengers detecting unit (not shownin the figure), and vehicle information sent thereto from a vehicleinformation extracting unit (not shown in the figure). The result of thedetermination acquired by this passable or impassable determining unit37 is sent to the control part 30.

The forwardly-existing sign detecting unit 38 detects whether or notthere exists a sign, and a character string showing the position of thesign and the information written on the sign (the distance to an exit orthe name of the exit displayed on the sign) on the basis of the signsignal sent thereto from the forwardly-existing sign detecting camera15, and sends the results of the detection to the control part 30 assign data.

The guidance time adjusting unit 39 adjusts a guidance time on the basisof information showing that the current position has been determined tobe a position where a guidance has to be provided from both the currentposition detected by the current position detecting unit 32 and theroute shown by the route data stored in the route storage unit 34,pieces of HOV lane related information acquired from the HOV lanedetermining unit 35, the HOV lane entrance and exit extracting unit 36,and the passable or impassable determining unit 37, the informationacquired from the forwardly-existing sign detecting unit 38, and so on.When determining that the guidance time has come, the guidance timeadjusting unit sends guidance time data showing that the guidance timehas come to the display processing unit 40 and to the voice messagegenerating unit 41 via the control part 30.

When the guidance time data are sent thereto from the guidance timeadjusting unit 39, the display processing unit 40 generates display datafor displaying the map shown by the map data from the map data acquiringunit 31, the route shown by the route data from the route storage unit34, and the pieces of information about the guidance point acquired fromthe results of the processes carried out by the HOV lane determiningunit 35, the HOV lane entrance and exit extracting unit 36, the passableor impassable determining unit 37, and the forwardly-existing signdetecting unit 38. The display data generated by this display processingunit 40 are sent to the display control unit 24 disposed in the controlunit 19.

When the guidance time data are sent thereto from the guidance timeadjusting unit 39, the voice message generating unit 41 generates avoice message for providing guidance on the route shown by the routedata from the route storage unit 34, and the pieces of information aboutthe guidance point acquired from the results of the processes carriedout by the HOV lane determining unit 35, the HOV lane entrance and exitextracting unit 36, the passable or impassable determining unit 37, andthe forwardly-existing sign detecting unit 38. The voice messagegenerated by this voice message generating unit 41 is sent to the voiceguidance unit 42 as voice data.

The voice guidance unit 42 converts the voice data sent thereto from thevoice message generating unit 41 into a voice signal, and sends thisvoice signal to the sound output unit 18. As a result, voice guidancecorresponding to the voice message is outputted from the sound outputunit 18.

The branch-on-HOV-lane extracting unit (branch extracting unit) 43extracts a branch point on the HOV lane which exists ahead of thevehicle on the basis of both the map data acquired by the map dataacquiring unit 31 and the current position of the vehicle detected bythe current position detecting unit 32. The result of the extraction ofa branch on the HOV lane acquired by the branch-on-HOV-lane extractingunit 43 is sent to the control part 30.

Next, an operation of the navigation device will be explained. FIG. 3 isa flow chart showing an operation of the navigation device in accordancewith Embodiment 1. An explanation of a guiding process of providingguidance on a lane change between an HOV lane and a normal lane will bemade. When the guiding process is started, map data are acquired first(step ST1). More specifically, the map data acquiring unit 31 acquiresmap data from the map data storage unit 16, and sends the map data tothe current position detecting unit 32 and to the HOV lane determiningunit 35.

Vehicle position information is then acquired (step ST2). Morespecifically, the current position detecting unit 32 detects the currentposition of the vehicle on the basis of either the current positionsignal sent thereto from the GPS receiver 12 or a current positionsignal which the current position detecting unit generates with deadreckoning by using the heading signal sent thereto from the headingsensor 13 and the distance signal sent thereto from the distance sensor14, and the map data acquired from the map data processing unit 31, andnotifies the current position of the vehicle to the control part 30 asvehicle position information. At this time, the HOV lane determiningunit 35 determines whether or not an HOV lane is included in either theroad included in the map data acquired by the map data acquiring unit 31or the route shown by the route data stored in the route storage unit34, and sends the result of the determination acquired thereby to thecontrol part 30.

After that, the position of a lane changing permitted section in whichthe vehicle is permitted to make a lane change between the HOV lane anda normal lane or the position of a branch point on the HOV lane isacquired (step ST3). More specifically, when the result of thedetermination carried out by the HOV lane determining unit 35 sentthereto from the control part 30 shows that an HOV lane is included inthe road, the HOV lane entrance and exit extracting unit 36 extracts anentrance and exit section which exists ahead of the vehicle, and inwhich the vehicle is permitted to make a lane change between a normallane and the HOV lane, and notifies the entrance and exit section to thecontrol part 30 as entrance and exit position data. The control part 30acquires the section shown by the entrance and exit position data sentthereto from the HOV lane entrance and exit extracting unit 36 as a lanechanging permitted section. As an alternative, when the result of thedetermination carried out by the HOV lane determining unit 35 sentthereto from the control part 30 shows that an HOV lane is included inthe road, the branch-on-HOV-lane extracting unit 43 extracts a branchpoint on the HOV lane which exists ahead of the vehicle, and notifiesthe branch point to the control part 30 as branch point position data.The control part 30 acquires the position shown by the branch pointposition data sent thereto from the branch-on-HOV-lane extracting unit43 as a branch point on the HOV lane.

Then, guidance on either a lane change for the lane changing permittedsection in which the vehicle is permitted to make a lane change betweenthe HOV lane and a normal lane, or a branch for the branch point on theHOV lane is provided (step ST4). More specifically, the control part 30provides guidance on either a lane change in the lane changing permittedsection acquired in step ST3 or a branch at the branch point on the HOVlane acquired in step ST3. More specifically, the control part provideseither exit guidance notifying that the vehicle can exit the HOV lane orentrance guidance notifying that the vehicle can enter the HOV lane, orbranch guidance notifying that there is a branch on the HOV lane for theuser.

As previously explained, because the navigation device in accordancewith the present invention can provide either exit guidance notifyingthat the vehicle can exit an HOV lane or entrance guidance notifyingthat the vehicle can enter an HOV lane, or branch guidance notifyingthat there is a branch on an HOV lane for the user, the navigationdevice in accordance with the present invention can provide either theexit guidance notifying that the vehicle can exit an HOV lane into anormal lane or the entrance guidance notifying that the vehicle canenter an HOV lane from a normal lane, or the branch guidance notifyingthat there is a branch on an HOV lane for the user when the vehiclereaches a position appropriate for providing the guidance.

Embodiment 2.

A navigation device in accordance with Embodiment 2 of the presentinvention is constructed in such a way as to provide guidance on a lanechange between an HOV lane and a normal lane with reference to theposition of a start point of a lane changing permitted section in whicha vehicle is permitted to make a lane change between the HOV lane andthe normal lane. The navigation device in accordance with Embodiment 2of the present invention has the same structure as that of thenavigation device in accordance with Embodiment 1 shown in FIGS. 1 and2.

FIG. 4 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 2 of the present invention, focusing on aguiding process. Hereafter, steps in each of which the same process in acorresponding step shown in the flow chart of FIG. 3 is carried out aredesignated by the same reference characters as those shown in FIG. 3,and the explanation of the steps will be simplified. When the guidingprocess is started, map data are acquired first (step ST1). Vehicleposition information is then acquired (step ST2).

The position of a lane changing permitted section in which the vehicleis permitted to make a lane change between an HOV lane and a normal laneis then acquired (step ST3 a). More specifically, when the result ofdetermination sent from an HOV lane determining unit 35 shows that anHOV lane is included in the road, an HOV lane entrance and exitextracting unit 36 extracts an entrance and exit section which existsahead of the vehicle, and in which the vehicle is permitted to make alane change between a normal lane and the HOV lane, and notifies theentrance and exit section to a control part 30 as entrance and exitposition data. The control part 30 acquires the section shown by theentrance and exit position data sent thereto from the HOV lane entranceand exit extracting unit 36 as a lane changing permitted section. As analternative, when the result of the determination carried out by the HOVlane determining unit 35 sent thereto from the control part 30 showsthat an HOV lane is included in the road, a branch-on-HOV-laneextracting unit 43 extracts a branch point on the HOV lane which existsahead of the vehicle, and notifies the branch point to the control part30 as branch point position data. The control part 30 also acquires theposition shown by the branch point position data sent thereto from thebranch-on-HOV-lane extracting unit 43 as a branch point on the HOV lane.

Then, guidance on a lane change is provided with reference to theposition of the start point of the lane changing permitted section inwhich the vehicle is permitted to make a lane change between the HOVlane and a normal lane (step ST4 a). More specifically, the control part30 provides guidance on a lane change with reference to the position ofthe start point of the lane changing permitted section acquired in stepST3 a. In this case, the position of the start point of the lanechanging permitted section indicates the start point of a section, asshown in FIG. 5, in which the vehicle is permitted to go back and forthbetween the HOV lane and the normal lane. As an alternative, the controlpart 30 provides guidance on the branch point on the HOV lane withreference to the position of the branch point on the HOV lane acquiredin step ST3 a. After that, the navigation device ends the guidingprocess.

As previously explained, the navigation device in accordance withEmbodiment 2 of the present invention can set up an effective guidancereference point when providing guidance on a lane changing permittedsection whether at the time of providing no route guidance or at thetime of providing route guidance. Because there is actually provided asign at the start point of a lane changing permitted section in whichthe vehicle is permitted to make a lane change between an HOV lane and anormal lane, and the navigation device in accordance with Embodiment 2of the present invention provides guidance on the lane changingpermitted section when the vehicle reaches the start point, thenavigation device enables the user to afford to make a lane change toenter or exit the HOV lane, thereby enabling the user to drive thevehicle with safety. In addition, the present embodiment is effectivealso for guidance on a branch point on an HOV lane.

Embodiment 3.

A navigation device in accordance with Embodiment 3 of the presentinvention is constructed in such a way as to determine a reference pointwith reference to which to provide guidance according to the length of alane changing permitted section. The structure of the navigation devicein accordance with this Embodiment 4 is the same as that of thenavigation device in accordance with Embodiment 1 shown in FIGS. 1 and2.

FIG. 6 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 3, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 3 is carried out are designated by the samereference characters as those shown in FIG. 3, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). Theposition of a lane changing permitted section in which a vehicle ispermitted to make a lane change between an HOV lane and a normal lane isthen acquired (step ST3 b). The length (distance) of the lane changingpermitted section is then acquired from the position of the lanechanging permitted section acquired in step ST3 b (step ST4 b). Morespecifically, a control part 30 acquires the length of the section shownby entrance and exit position data sent thereto from an HOV laneentrance and exit extracting unit 36 as the length of the lane changingpermitted section.

It is then checked to see whether or not the lane changing permittedsection is short (step ST5 b). Concretely, it is checked to see whetheror not the distance of the lane changing permitted section acquired instep ST4 b is shorter than, for example, 0.6 miles. When it isdetermined in this step ST5 b that the lane changing permitted sectionis short, guidance is provided with reference to the position of thestart point of the lane changing permitted section in which the vehicleis permitted to make a lane change between the HOV lane and the normallane (step ST6 b). More specifically, the control part 30 providesguidance on a lane change between the HOV lane and the normal lane withreference to the position of the start point. After that, the controlpart ends the guiding process.

In contrast, when it is determined in above-mentioned step ST5 b thatthe lane changing permitted section is not short, guidance is providedwith reference to a point at a distance (e.g. 0.6 miles) adequate toenable the user to make a lane change before reaching the end point ofthe lane changing permitted section (step ST7 b). More specifically, thecontrol part 30 provides guidance on a lane change between the HOV laneand the normal lane with reference to the point. After that, the controlpart ends the guiding process.

As previously explained, the navigation device in accordance withEmbodiment 3 of the present invention can carry out provide guidance onexit from an HOV lane at a point appropriate for the user inconsideration of the length of a lane changing permitted section inwhich the vehicle is permitted to make a lane change between the HOVlane and a normal lane whether at the time of providing no routeguidance or at the time of providing route guidance. In this embodiment,as an example of a point appropriate for the user, when the lanechanging permitted section is short, the start point of the lanechanging permitted section can be defined, whereas when the lanechanging permitted section is long, a point at an adequate distanceprovided in order to enable the user to make a lane change with safetybefore reaching the end point of the lane changing permitted section canbe defined.

Once the user starts traveling in an HOV lane, the user usually wants tocontinue traveling in the HOV lane as long as possible until exiting theHOV lane, but the user desires to exit the HOV lane with safety. Inorder to respond these demands of users, the navigation device inaccordance with Embodiment 3 provides guidance on a lane change in alane changing permitted section at a point which the navigation devicedetermines in consideration of the distance of the lane changingpermitted section and a distance at which the user can make a lanechange in the lane changing permitted section with safety. As a result,the navigation device enables the user to travel in an HOV lane as longas possible with safety.

Embodiment 4.

A navigation device in accordance with Embodiment 4 of the presentinvention is constructed in such a way as to determine a reference pointwith reference to which to provide guidance according to the length of alane changing permitted section to provide different guidance accordingto the reference point. The structure of the navigation device inaccordance with this Embodiment 4 is the same as that of the navigationdevice in accordance with Embodiment 1 shown in FIGS. 1 and 2.

FIG. 7 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 4, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 3 is carried out are designated by the samereference characters as those shown in FIG. 3, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). More specifically, a routesearching unit 33 searches for a route leading from the current positionof a vehicle shown by the vehicle position information acquired from acurrent position detecting unit 32 in step ST2 to a destination inputtedfrom an input unit 11 on the basis of the map data acquired from a mapdata acquiring unit 31 in step ST1, and sends route data showing theroute acquired through this search to a route storage unit 34 to makethis route storage unit store the route data. The process of this stepST3 c is skipped at the time of providing no route guidance (when notproviding any guidance when the vehicle is traveling along the route).

It is then checked to see whether an HOV lane exists ahead of thevehicle or on the route (step ST4 c). More specifically, an HOV lanedetermining unit 35 determines whether or not an HOV lane is included ineither the road included in the map data acquired from the map dataacquiring unit 31 in step ST1 or the route shown by the route datastored in the route storage unit 34 in step ST3 c, and then sends theresult of this determination to a control part 30. The determination ofwhether or not an HOV lane is included in the route is effective onlywhen the route searching process of step ST3 c is carried out. Thecontrol part 30 checks to see whether or not an HOV lane exists ahead ofthe vehicle or on the route on the basis of the result of thedetermination acquired by the HOV lane determining unit 35. When it isdetermined in step ST4 c that no HOV lane exists ahead of the vehicle orno HOV lane exists on the route, the navigation device ends the guidingprocess.

In contrast, when it is determined in step ST4 c that an HOV lane existsahead of the vehicle or on the route, the position of a lane changingpermitted section in which the vehicle is permitted to make a lanechange between the HOV lane and a normal lane is then acquired (step ST5c). The length (distance) of the lane changing permitted section inwhich the vehicle is permitted to make a lane change between the HOVlane and the normal lane is then acquired (step ST6 c). It is thenchecked to see whether or not the lane changing permitted section inwhich the vehicle is permitted to make a lane change between the HOVlane and the normal lane is long (step ST7 c). More specifically, thecontrol part 30 checks to see whether or not the distance of the lanechanging permitted section acquired in step ST6 c is equal to or longerthan 3 miles.

When it is determined in this step ST7 c that the lane changingpermitted section in which the vehicle is permitted to make a lanechange between the HOV lane and the normal lane is long, guidance onexit from the HOV lane or entrance into the HOV lane is provided withreference to an exit, a branch point, or a highway entrance start pointconnected to the road on the route (step ST8 c). More specifically, thecontrol part 30 provides guidance on exit from the HOV lane or entranceinto the HOV lane with reference to either a branch point, such as ahighway exit on the route, or a highway entrance start point wherevehicles traveling from a general road enters the highway, instead ofthe start point of the lane changing permitted section in which thevehicle is permitted to make a lane change between the HOV lane and thenormal lane, or the like. FIGS. 8 and 9 show examples in which there isa long lane changing permitted section in which the vehicle is permittedto make a lane change between an HOV lane and a normal lane. An exitfrom an HOV lane with reference to a highway exit is considered in theexample shown in FIG. 8, while entrance into an HOV lane with referenceto a highway entrance start point is considered in the example shown inFIG. 9. After that, the navigation device ends the guiding process.

In contrast, when it is determined in above-mentioned step ST7 c thatthe lane changing permitted section in which the vehicle is permitted tomake a lane change between the HOV lane and the normal lane is not long,guidance on exit/entrance between the HOV lane and the normal lane isprovided regardless of the distance of the lane changing permittedsection (step ST9 c). After that, the navigation device ends the guidingprocess.

As explained above, the navigation device in accordance with Embodiment4 of the present invention can provide guidance on exit from an HOV lanewith reference to an exit or a branch point on the route when thevehicle reaches a point appropriate for the user. In this embodiment, asan example of a point appropriate for the user, a point located in adirection of a place of departure (in a direction of the vehicle) withrespect to the position of an exit on the route and at a distanceadequate to enable the user to make a lane change, or a point located ina direction of the place of departure (in a direction of the vehicle)with respect to the position of a branch and at a distance adequate toenable the user to make a lane change can be defined.

Once the user starts traveling in an HOV lane, the user usually wants tocontinue traveling in the HOV lane as long as possible until exiting theHOV lane, but the user desires to exit the HOV lane with safety. Inorder to respond these demands of users, the navigation device inaccordance with Embodiment 4 provides guidance on a lane change withreference to a branch or an exit existing ahead of an HOV lane which thevehicle will exit. As a result, the navigation device enables the userto travel in an HOV lane as long as possible with safety.

Further, the navigation device in accordance with Embodiment 4 of thepresent invention provides guidance on entrance into an HOV lane withreference to a highway entrance start point when the vehicle reaches apoint appropriate for the user. In this case, as an example of a pointappropriate for the user, a point located in a direction of adestination (in a direction of the heading of the vehicle) with respectto the position of a highway entrance start point on the route and at adistance adequate to enable the user to make a lane change can bedefined.

In order to enable the user to enter an HOV lane with safety when theuser desires to enter the HOV lane, instead of immediately providingguidance on entrance into the HOV lane at a highway entrance startpoint, the navigation device provides guidance by taking intoconsideration a distance in a direction of the destination with respectto the position of the highway entrance start point and adequate toenable the user to make a lane change from a normal lane when enteringthe HOV lane. As a result, the navigation device enables the user tostart traveling in an HOV lane as early as possible with safety.

Because a typical road in which an HOV lane is disposed has a largenumber of normal lanes, and it is therefore difficult for the user toeasily make lane changes to a lane which is next to the HOV lane, it isnecessary to define a distance where the user can make a lane change inthe normal lanes with safety as the distance adequate to enable the userto make a lane change.Embodiment 5.

A navigation device in accordance with Embodiment 5 of the presentinvention is constructed in such a way as not to provide any guidance onexit/entrance between an HOV lane and a normal lane in a lane changingpermitted section in which a vehicle is permitted to make a lane changebetween the HOV lane and the normal lane when the lane changingpermitted section is long. The structure of the navigation device inaccordance with this Embodiment 5 is the same as that of the navigationdevice in accordance with Embodiment 1 shown in FIGS. 1 and 2.

FIG. 10 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 5, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 7 is carried out are designated by the samereference characters as those shown in FIG. 7, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). It is then checked to seewhether an HOV lane exists ahead of a vehicle or on a route (step ST4c). When it is determined in this step ST4 c that no HOV lane existsahead of the vehicle or no HOV lane exists on the route, the navigationdevice ends the guiding process.

In contrast, when it is determined in step ST4 c that an HOV lane existsahead of the vehicle or on the route, the position of a lane changingpermitted section in which the vehicle is permitted to make a lanechange between the HOV lane and a normal lane is then acquired (step ST5c). The length (distance) of the lane changing permitted section inwhich the vehicle is permitted to make a lane change between the HOVlane and the normal lane is then acquired (step ST6 c).

It is then checked to see whether or not the lane changing permittedsection in which the vehicle is permitted to make a lane change betweenthe HOV lane and the normal lane is long (step ST7 c). Concretely,whether or not the distance of the lane changing permitted sectionacquired in step ST6 c is equal to or longer than 3 miles is checked tosee. In this case, “the lane changing permitted section is long” meansthat the HOV lane and the normal lane are separated by a white dottedline along the whole road, and the vehicle is permitted to make a lanechange for exit/entrance between the HOV lane and the normal lane at anarbitrary position in the lane changing permitted section.

When it is determined in step ST7 c that the lane changing permittedsection in which the vehicle is permitted to make a lane change betweenthe HOV lane and the normal lane is long, no guidance on exit/entrancebetween the HOV lane and the normal lane is provided (step ST8 d). Morespecifically, because the vehicle can make a lane change at an arbitraryposition between the HOV lane and the normal lane when the lane changingpermitted section in which the vehicle is permitted to make a lanechange between the HOV lane and the normal lane is long, the navigationdevice does not necessarily have to provide any guidance. Therefore, noguidance on exit/entrance between the HOV lane and the normal lane isprovided. The navigation device can be constructed in such a way as notto, in this step ST8 d, provide only any guidance on exit, only anyguidance on entrance, or both any guidance on exit and any guidance onentrance. After that, the navigation device ends the guiding process.

In contrast, when it is determined in above-mentioned step ST7 c thatthe lane changing permitted section in which the vehicle is permitted tomake a lane change between the HOV lane and the normal lane is not long,guidance on exit/entrance between the HOV lane and the normal lane isprovided regardless of the distance of the lane changing permittedsection in which the vehicle is permitted to make a lane change betweenthe HOV lane and the normal lane (step ST9 c). After that, thenavigation device ends the guiding process.

As previously explained, when the user can freely make a lane changebetween an HOV lane and a normal lane, the navigation device inaccordance with Embodiment 5 of the present invention enables the userto make a lane change according to the user's liking, like in a case inwhich the user makes a lane change between normal lanes. Therefore, thenavigation device can prevent any guidance from being provided uselesslyfor the user.

Embodiment 6.

A navigation device in accordance with Embodiment 6 of the presentinvention is constructed in such a way as to determine whether or not toprovide guidance on exit/entrance between an HOV lane and a normal lanein a lane changing permitted section in which a vehicle is permitted tomake a lane change between the HOV lane and the normal lane according toa setting made by the user when the lane changing permitted section islong. The structure of the navigation device in accordance with thisEmbodiment 6 is the same as that of the navigation device in accordancewith Embodiment 1 shown in FIGS. 1 and 2.

FIG. 11 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 6, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 10 is carried out are designated by the samereference characters as those shown in FIG. 10, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). It is then checked to seewhether an HOV lane exists ahead of a vehicle or on a route (step ST4c). When it is determined in this step ST4 c that no HOV lane existsahead of the vehicle or no HOV lane exists on the route, the navigationdevice ends the guiding process.

In contrast, when it is determined in step ST4 c that an HOV lane existsahead of the vehicle or on the route, the position of a lane changingpermitted section in which the vehicle is permitted to make a lanechange between the HOV lane and a normal lane is then acquired (step ST5c). The length (distance) of the lane changing permitted section inwhich the vehicle is permitted to make a lane change between the HOVlane and the normal lane is then acquired (step ST6 c).

It is then checked to see whether or not the lane changing permittedsection in which the vehicle is permitted to make a lane change betweenthe HOV lane and the normal lane is long (step ST7 c). When it isdetermined in this step ST7 c that the lane changing permitted sectionin which the vehicle is permitted to make a lane change between the HOVlane and the normal lane is not long, guidance on exit/entrance betweenthe HOV lane and the normal lane is provided regardless of the distanceof the lane changing permitted section (step ST9 c). After that, thenavigation device ends the guiding process.

In contrast, when it is determined in step ST7 c that the lane changingpermitted section in which the vehicle is permitted to make a lanechange between the HOV lane and the normal lane is long, it is thenchecked to see whether a setting of not providing any guidance onexit/entrance from and into the HOV lane when the lane changingpermitted section is long has been made (step ST7 c-1). Morespecifically, when the lane changing permitted section is long, acontrol part 30 checks to see whether the user has made a setting of notproviding any guidance on exit/entrance from and into the HOV lane. Theuser is allowed to make this setting by using, for example, an inputunit 11. The input unit 11 which the user uses when making a setting ofnot providing any guidance on exit/entrance from and into the HOV lanefunctions as a setting unit in accordance with the present invention.

When it is determined in this step ST7 c-1 that a setting of notproviding any guidance on exit/entrance from and into the HOV lane whenthe lane changing permitted section is long has been made, no guidanceon exit/entrance between the HOV lane and the normal lane is provided(step ST8 d). The navigation device can be constructed in such a way asnot to, in this step ST8 d, provide only any guidance on exit, only anyguidance on entrance, or both any guidance on exit and any guidance onentrance. After that, the navigation device ends the guiding process.

In contrast, when it is determined in above-mentioned step ST7 c-1 thatno setting of not providing any guidance on exit/entrance from and intothe HOV lane when the lane changing permitted section is long has beenmade, guidance on exit from the HOV lane or entrance into the HOV laneis provided with reference to an exit, a branch point, or a highwayentrance start point connected to the road on the route (step ST10 d).The process of this step ST10 d is the same as that of step ST8 c of theguiding process (refer to FIG. 7) carried out by the navigation devicein accordance with above-mentioned Embodiment 4. After that, thenavigation device ends the guiding process.

As explained above, because the navigation device in accordance withEmbodiment 6 of the present invention is constructed in such a way as tochange whether or not to provide guidance on exit and guidance onentrance according to a setting made by the user, the navigation devicecan suit itself to the user's request.

Embodiment 7.

A navigation device in accordance with Embodiment 7 of the presentinvention is constructed in such a way as to provide guidance on anadvance preparation when the user enters an HOV lane from a normal lane.The structure of the navigation device in accordance with thisEmbodiment 7 is the same as that of the navigation device in accordancewith Embodiment 1 shown in FIGS. 1 and 2.

FIG. 12 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 7, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 7 is carried out are designated by the samereference characters as those shown in FIG. 7, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance. It is thenchecked to see whether or not a vehicle is traveling in a normal lane ofa road in which an HOV lane is running parallel with the normal lane(step ST4 e). More specifically, an HOV lane determining unit 35determines whether or not an HOV lane is included in the road includedin the map data from a map data acquiring unit 31, and sends the resultof the determination to a control part 30. The control part 30 checks tosee whether the result of the determination received from the HOV lanedetermining unit 35 shows that an HOV lane is included in the road andwhether or not the current position shown by the vehicle positioninformation received in step ST2 is on the normal lane running parallelwith the HOV lane.

When it is determined in this step ST4 e that the vehicle is nottraveling in a normal lane of the road in which an HOV lane is runningparallel with the normal lane, the navigation device ends the guidingprocess. In contrast, when it is determined in step ST4 e that thevehicle is traveling in a normal lane of the road in which an HOV laneis running parallel with the normal lane, it is then checked to seewhether there exists a lane changing permitted section in which thevehicle is permitted to enter the HOV lane ahead of the vehicle or onthe route (step ST5 e). More specifically, when the result of thedetermination sent thereto from the HOV lane determining unit 35 showsthat an HOV lane is included in the road or an HOV lane exists on theroute, an HOV lane entrance and exit extracting unit 36 extracts anentrance and exit section in which the vehicle is permitted to make alane change between a normal lane and the HOV lane. The entrance andexit section extracted by this HOV lane entrance and exit extractingunit 36 is notified to the control part 30 as entrance and exit positiondata. The control part 30 checks to see whether there exists a lanechanging permitted section in which the vehicle is permitted to enter anHOV lane ahead of the vehicle or on the route on the basis of theentrance and exit position data from the HOV lane entrance and exitextracting unit 36. When it is determined in this step ST5 e that nolane changing permitted section in which the vehicle is permitted toenter an HOV lane exits ahead of the vehicle, or no lane changingpermitted section in which the vehicle is permitted to enter an HOV laneexits on the route, the navigation device ends the guiding process.

In contrast, when it is determined in this step ST5 e that a lanechanging permitted section in which the vehicle is permitted to enter anHOV lane exits ahead of the vehicle or on the route, the position of thelane changing permitted section in which the vehicle is permitted toenter the HOV lane is then acquired (step ST6 e). More specifically, theHOV lane entrance and exit extracting unit 36 extracts the entrance andexit section in which the vehicle is permitted to make a lane changebetween a normal lane and the HOV lane which exists ahead of thevehicle, and notifies the entrance and exit section to the control part30 as entrance and exit position data. The control part 30 acquires thesection shown by the entrance and exit position data sent thereto fromthe HOV lane entrance and exit extracting unit 36 as a lane changingpermitted section in which the vehicle is permitted to enter the HOVlane from the normal lane.

Guidance indicating that the user should get closer to the HOV lanewithin the normal lane before reaching the lane changing permittedsection in which the vehicle is permitted to enter the HOV lane isprovided (step ST7 e). This guidance indicating that the user should getcloser to the HOV lane within the normal lane corresponds to theguidance on an advance preparation in accordance with the presentinvention. Guidance on entrance into the HOV lane is then provided (stepST8 e). After that, the navigation device ends the guiding process.

As previously explained, because the navigation device in accordancewith Embodiment 7 of the present invention is constructed in such a wayas to separately provide both guidance on an advance preparation forentrance into an HOV lane, and guidance on entrance into the HOV lane,the navigation device makes it possible for the user to be aware thatthe user should make a lane change in advance, thereby being able toprevent the user from being in danger of hastily making a lane change tothe HOV lane.

Embodiment 8.

A navigation device in accordance with Embodiment 8 of the presentinvention is constructed in such a way as to provide guidance onentrance into an HOV lane at a time according to the number of laneswhen a vehicle is traveling in a normal lane. The structure of thenavigation device in accordance with this Embodiment 8 is the same asthat of the navigation device in accordance with Embodiment 1 shown inFIGS. 1 and 2.

FIG. 13 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 8, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 12 is carried out are designated by the samereference characters as those shown in FIG. 12, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance. It is thenchecked to see whether or not the vehicle is traveling in a normal laneof a road in which an HOV lane is running parallel with the normal lane(step ST4 e). When it is determined in this step ST4 e that the vehicleis not traveling in a normal lane of the road in which an HOV lane isrunning parallel with the normal lane, the navigation device ends theguiding process.

In contrast, when it is determined in step ST4 e that the vehicle istraveling in a normal lane of the road in which an HOV lane is runningparallel with the normal lane, it is then checked to see whether thereexists a lane changing permitted section in which the vehicle ispermitted to enter the HOV lane ahead of the vehicle or on the route(step ST5 e). When it is determined in this step ST5 e that no lanechanging permitted section in which the vehicle is permitted to enterthe HOV lane exits ahead of the vehicle, or no lane changing permittedsection in which the vehicle is permitted to enter an HOV lane exits onthe route, the navigation device ends the guiding process.

In contrast, when it is determined in step ST5 e that a lane changingpermitted section in which the vehicle is permitted to enter the HOVlane exits ahead of the vehicle or on the route, the position of thelane changing permitted section in which the vehicle is permitted toenter the HOV lane is then acquired (step ST6 e).

The number of normal lanes of the road which the vehicle is traveling isthen acquired (step ST7 e-1). More specifically, a control part 30acquires the number of normal lanes of the road from the map dataacquired from a map data acquiring unit 31 in step ST1. Next, guidanceindicating that the vehicle should get closer to the HOV lane isprovided according to the number of normal lanes acquired in step ST7e-1 before the vehicle reaches the lane changing permitted section inwhich the vehicle is permitted to enter the HOV lane (step ST7 e-2). Forexample, when the number of normal lanes is small, the guidanceindicating that the vehicle should get closer to the HOV lane can beprovided at a somewhat late time before the vehicle reaches the lanechanging permitted section. The control part can be alternativelyconstructed in such a way as not to provide the guidance when the numberof normal lanes is small, such as 2. In contrast with this, because asudden provision of the guidance on entrance into the HOV lane makes itdifficult for the user to smoothly make lane changes to the HOV lanewhen the number of normal lanes is large, the control part provides theguidance at an earlier time before the vehicle reaches the lane changingpermitted section. Thus, the navigation device provides the guidance inone of the different ways depending on the number of normal lanes.

Then, because the user ought to have completed lane changes to thenormal lane which is next to the HOV lane through the above-mentionedprocesses, guidance on entrance into the HOV lane is provided (step ST8e). After that, the navigation device ends the guiding process.

As previously explained, the navigation device in accordance withEmbodiment 8 of the present invention changes the time that thenavigation device provides guidance on an advance preparation forentrance into an HOV lane according to the number of normal lanes,thereby being able to prevent the guidance from being provided at aninappropriate time, such as at a too early time or at a too late time.Generally, it doesn't matter if the guidance indicating that the vehicleshould get closer to the HOV lane is provided at a somewhat late timewhen the number of normal lanes is small. Further, the navigation devicecan be constructed in such a way as not to provide the guidance when thenumber of normal lanes is small, such as 2. In contrast with this,because a sudden provision of the guidance on entrance into the HOV lanemakes it difficult for the user to smoothly make lane changes to the HOVlane when the number of normal lanes is large, it is effective toprovide the guidance at an earlier time.

Embodiment 9.

A navigation device in accordance with Embodiment 9 of the presentinvention is constructed in such a way as to provide guidance onentrance into an HOV lane when a vehicle is traveling in a normal laneby assuming that the number of normal lanes is a maximum number oflanes, e.g. ten in the structure of the navigation device in accordancewith Embodiment 7. The structure of the navigation device in accordancewith this Embodiment 9 is the same as that of the navigation device inaccordance with Embodiment 1 shown in FIGS. 1 and 2.

FIG. 14 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 9, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 12 is carried out are designated by the samereference characters as those shown in FIG. 12, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance. It is thenchecked to see whether or not the vehicle is traveling in a normal laneof a road in which an HOV lane is running parallel with the normal lane(step ST4 e). When it is determined in this step ST4 e that the vehicleis not traveling a normal lane of the road in which an HOV lane isrunning parallel with the normal lane, the navigation device ends theguiding process.

In contrast, when it is determined in step ST4 e that the vehicle istraveling a normal lane of the road in which an HOV lane is runningparallel with the normal lane, it is then checked to see whether thereexists a lane changing permitted section in which the vehicle ispermitted to enter the HOV lane ahead of the vehicle or on the route(step ST5 e). When it is determined in this step ST5 e that no lanechanging permitted section in which the vehicle is permitted to enterthe HOV lane exits ahead of the vehicle, or no lane changing permittedsection in which the vehicle is permitted to enter an HOV lane exits onthe route, the navigation device ends the guiding process.

In contrast, when it is determined in this step ST5 e that a lanechanging permitted section in which the vehicle is permitted to enterthe HOV lane exits ahead of the vehicle or on the route, the position ofthe lane changing permitted section in which the vehicle is permitted toenter the HOV lane is then acquired (step ST6 e).

Next, guidance indicating that the vehicle should get closer to the HOVlane is provided at a time which is determined by assuming that thenumber of normal lanes is 10 before the vehicle reaches the lanechanging permitted section in which the vehicle is permitted to enterthe HOV lane (step ST7 f).

More specifically, a control part 30 assumes the maximum number of lanesto be a fixed number (e.g. ten), and provides guidance indicating thatthe vehicle should get closer to the HOV lane at a time which thecontrol part determines in consideration of the time required for thevehicle to move throughout the assumed number of lanes, and before thevehicle reaches the lane changing permitted section in which the vehicleis permitted to enter the HOV lane. By thus providing the guidance inconsideration of the maximum number of lanes, the navigation device canprevent the user from making forcible lane changes.

Then, because the user ought to have completed lane changes to thenormal lane which is next to the HOV lane through the above-mentionedprocesses, guidance on entrance into the HOV lane is provided (step ST8e). After that, the navigation device ends the guiding process.

As previously explained, because the navigation device in accordancewith Embodiment 9 of the present invention is constructed in such a wayas to separately provide both guidance on an advance preparation forentrance into an HOV lane, and guidance on entrance into the HOV lane,the navigation device makes it possible for the user to be aware thatthe user should make lane changes in advance, thereby being able toprevent the user from being in danger of hastily making lane changes tothe HOV lane. Further, by determining the time that the navigationdevice provides guidance according to the maximum number of lanes, thenavigation device can prevent the user from being in danger of makingforcible lane changes, and can notify guidance information to the userat the same timing.

Embodiment 10.

A navigation device in accordance with Embodiment 10 of the presentinvention is constructed in such a way as to provide guidance on anadvance preparation when the user exits an HOV lane to a normal lane.The structure of the navigation device in accordance with thisEmbodiment 10 is the same as that of the navigation device in accordancewith Embodiment 1 shown in FIGS. 1 and 2.

FIG. 15 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 10, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 13 is carried out are designated by the samereference characters as those shown in FIG. 13, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance. It is thenchecked to see whether or not a vehicle is traveling in an HOV lane(step ST4 g). More specifically, an HOV lane determining unit 35determines whether or not an HOV lane is included in the road includedin the map data from a map data acquiring unit 31, and sends the resultof the determination to a control part 30. The control part 30 checks tosee whether the result of the determination received from the HOV lanedetermining unit 35 shows that an HOV lane is included in the road, andwhether or not the current position shown by the vehicle positioninformation received in step ST2 is on the HOV lane. When it isdetermined in this step ST4 g that the vehicle is not traveling in anHOV lane, the navigation device ends the guiding process.

In contrast, when it is determined in step ST4 g that the vehicle istraveling in an HOV lane, it is then checked to see whether there existsa lane changing permitted section in which the vehicle is permitted toenter the normal lane ahead of the vehicle or on a route (step ST5 g).More specifically, when the result of the determination sent theretofrom the HOV lane determining unit 35 shows that an HOV lane is includedin the road or exists on the route, an HOV lane entrance and exitextracting unit 36 extracts an entrance and exit section in which thevehicle is permitted to make a lane change between the normal lane andthe HOV lane. The entrance and exit section extracted by this HOV laneentrance and exit extracting unit 36 is notified to the control part 30as entrance and exit position data. The control part 30 checks to seewhether there exists a lane changing permitted section in which thevehicle is permitted to enter the normal lane ahead of the vehicle or onthe route on the basis of the entrance and exit position data sentthereto from the HOV lane entrance and exit extracting unit 36. When itis determined in this step ST5 g that no lane changing permitted sectionin which the vehicle is permitted to enter the normal lane exists aheadof the vehicle, or no lane changing permitted section in which thevehicle is permitted to enter the normal lane exists on the route, thenavigation device ends the guiding process. The determination of whetherthere exists a lane changing permitted section in which the vehicle ispermitted to enter the normal lane on the route is effective only whenthe route search is carried out in step ST3 c.

In contrast, when it is determined in step ST5 g that there exists alane changing permitted section in which the vehicle is permitted toenter the normal lane ahead of the vehicle or on the route, the positionof the lane changing permitted section in which the vehicle is permittedto enter the normal lane is then acquired (step ST6 g). The number ofHOV lanes of the road which the vehicle is traveling is then acquired(step ST7 g). It is then checked to see whether or not the number of HOVlanes is one (step ST8 g). When it is determined in this step ST8 g thatthe number of HOV lanes is one, the navigation device ends the guidingprocess.

In contrast, when it is determined in step ST8 g that the number of HOVlanes is not one, guidance indicating that the user should get closer tothe normal lane before reaching the lane changing permitted section inwhich the vehicle is permitted to enter the normal lane is providedaccording to the number of lanes acquired in step ST7 g (step ST9 g).Because there is a case in which the vehicle is not permitted to make alane change between HOV lanes in a lane changing permitted section inwhich the vehicle is permitted to make a lane change between an HOV laneand a normal lane, depending on a road in which a HOV lane and a normallane is expressed by a single link (within the lane changing permittedsection, there is a section in which the vehicle is permitted to make alane change to a normal lane as long as the vehicle is traveling in alane (an HOV lane) adjacent (parallel) to the normal lanes), the vehicleneeds to move to the HOV lane adjacent (parallel) to the normal lanes inadvance.

Then, because the vehicle ought to have moved to the HOV lane which isthe nearest to the normal lanes (the HOV lane to the side of the normallanes) through the above-mentioned processes, guidance on exit to thenormal lanes is provided (step ST10 g). After that, the navigationdevice ends the guiding process.

As previously explained, because the navigation device in accordancewith Embodiment 10 of the present invention is constructed in such a wayas to separately provide both guidance on an advance preparation forexit from an HOV lane, and guidance on entrance into a normal lane, thenavigation device makes it possible for the user to be aware that theuser should make a lane change in advance, thereby being able to preventthe user from being in danger of hastily making lane changes to exit anHOV lane.

Embodiment 11.

A navigation device in accordance with Embodiment 11 of the presentinvention is constructed in such a way as to change a time when thenavigation device provides guidance and the number of times that thenavigation device provides the guidance according to whether or not avehicle is traveling in an HOV lane. The structure of the navigationdevice in accordance with this Embodiment 11 is the same as that of thenavigation device in accordance with Embodiment 1 shown in FIGS. 1 and2.

FIG. 16 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 11, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 15 is carried out are designated by the samereference characters as those shown in FIG. 15, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance. It is thenchecked to see whether or not the vehicle is traveling a road in whichan HOV lane and a normal lane are expressed by a single link (step ST4i). When it is determined in this step ST4 i that the vehicle is nottraveling a road in which an HOV lane and a normal lane are expressed bya single link, the navigation device ends the guiding process.

In contrast, when it is determined in step ST4 i that the vehicle is nottraveling a road in which an HOV lane and a normal lane are expressed bya single link, it is then checked to see whether or not the vehicle istraveling in an HOV lane (step ST4 g). When it is determined in thisstep ST4 g that the vehicle is traveling in an HOV lane, the time thatthe navigation device provides guidance is then set to be later thanthat when the vehicle is traveling in a normal lane (step ST5 h).

The number of times that the navigation device provides the guidance isthen reduced to be smaller than that when the vehicle is traveling in anormal lane (step ST6 h). The navigation device then provides theguidance the number of times set thereby at the guidance time setthereby (step ST7 h). After that, the navigation device ends the guidingprocess. The navigation device can be constructed in such a way as tocarry out either one of the processes of steps ST5 h and ST6 h.

When it is determined in above-mentioned step ST4 g that the vehicle isnot traveling in an HOV lane, the time that the navigation deviceprovides the guidance is then set to be earlier than that when thevehicle is traveling in an HOV lane (step ST8 i). More specifically, thetime that the navigation device provides the guidance is set to be thesame as the time that the navigation device provides other guidance. Thenumber of times that the navigation device provides the guidance is setto be the same as the number of times that the navigation deviceprovides guidance when the vehicle is traveling in a normal highway(step ST9 i). After that, the navigation device advances the sequence tostep ST7 h, and provides the guidance the number of times set thereby instep ST9 i at the guidance time set thereby in step ST8 i.

As previously explained, the navigation device in accordance withEmbodiment 11 of the present invention is effective for a case in whichthe number of HOV lanes is small fundamentally, and it is not necessaryto provide the user with a preparation (also including a mentalpreparation) for the next movement at an earlier time before reaching aguidance point. Further, because it can be assumed that the user caneasily drive the vehicle even if the navigation device does not provideany guidance (caution) repeatedly, the navigation device can reducediscomfort provided for the user more effectively and can provideappropriate guidance by setting different times when providing guidanceand different numbers of times that guidance is provided for HOV lanesand normal lanes. The present invention is effective not only forguidance on entrance/exit between an HOV lane and a normal lane, butalso for guidance on a branch on an HOV lane.

Variant 1 of Embodiment 11.

A navigation device in accordance with Variant 1 of Embodiment 11 of thepresent invention is constructed in such a way as to provide guidance ata time according to the number of lanes of a road which a vehicle istraveling. The structure of the navigation device in accordance withthis Variant 1 of Embodiment 11 is the same as that of the navigationdevice in accordance with Embodiment 1 shown in FIGS. 1 and 2.

FIG. 17 is a flow chart showing an operation of the navigation device inaccordance with Variant 1 of Embodiment 11, focusing on a guidingprocess. Hereafter, steps in each of which the same process in acorresponding step shown in the flow chart of FIG. 16 is carried out aredesignated by the same reference characters as those shown in FIG. 16,and the explanation of the steps will be simplified.

When the guiding process is started; map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance.

The number of lanes of the road which the vehicle is traveling is thenacquired (step ST4 j). In this case, when an HOV lane and a normal lanein the road are expressed by a single link and the vehicle is travelingin the HOV lane of the road, the number of lanes including only HOVlanes is acquired, whereas when the vehicle is traveling in the normallane of the road, the number of lanes including only normal lanes isacquired. Guidance is then provided at the time according to the numberof lanes (step ST5 j). After that, the navigation device ends theguiding process.

As previously explained, because there is a case in which the user needsto make a preparation, such as moving in a direction in which the usershould move (in a direction toward an HOV lane or a normal lane), at thenext guidance point when the vehicle is traveling a road with a largenumber of lanes, the navigation device in accordance with Variant 1 ofEmbodiment 11 of the present invention provides guidance at an earliertime when the vehicle is traveling a road with a larger number of lanes,whereas the navigation device provides guidance at a later time when thevehicle is traveling a road with a smaller number of lanes. Therefore,the navigation device makes it possible for the user to have a feelingof tension only within a time period during which the vehicle travels amoderate distance until reaching the guidance point.

Embodiment 12.

A navigation device in accordance with Embodiment 12 of the presentinvention is constructed in such a way as to provide guidance at a timeaccording to the position of a sign or the information written on asign. The structure of the navigation device in accordance with thisEmbodiment 12 is the same as that of the navigation device in accordancewith Embodiment 1 shown in FIGS. 1 and 2.

FIG. 18 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 12, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 16 is carried out are designated by the samereference characters as those shown in FIG. 16, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance.

The position of a sign on the road indicating the name of a destination,a road number or the like is then acquired (step ST4 k). The position ofthe sign can be acquired by using, for example, a method of acquiringthe sign position from information stored in a map data storage unit 16,a method of detecting the actual position of the sign by using aforwardly-existing sign detecting camera 15, or a method of storing arule governing where the sign is placed (e.g. how many meters from abranch the sign is located) and calculating the sign position by usingsoftware.

The information written on the sign is then acquired (step ST5 k). Morespecifically, a control part 30 acquires the information written on thesign, such as the name of a place, an exit, a road name or a distance,on the basis of the sign data sent thereto from the forwardly-existingsign detecting unit 38. However, when providing guidance independent ofthe information written on the sign by using only the position of thesign, the navigation device skips this process of step ST5 k.

Guidance is then provided according to either the position of the signor the information written on the sign (step ST6 k). More specifically,guidance is provided by taking into consideration both a time accordingto the position of the sign acquired in step ST4 k and a time accordingto the information written on the sign acquired in step ST5 k (i.e. atime according to a distance or the like written on the sign). As thisguidance, at least one of voice guidance, a guide map display, or atelop display is provided, like in the case of providing normalguidance. After that, the navigation device ends the guiding process.

As previously explained, because the navigation device in accordancewith Embodiment 12 of the present invention is constructed in such a wayas to change a guidance time according to the position of a sign, thenavigation device can provide guidance according to the position of asign. As a result, because the navigation device can provide guidancematching road information, the navigation device enables the user totravel with safety without feeling uncomfortable during travel.

Further, because the navigation device is constructed in such a way asto provide guidance according to a distance written on a sign showing anexit, the navigation device can provide guidance on the distancematching the sign information, the navigation device enables the user totravel with safety without feeling uncomfortable during travel.

Further, because the navigation device is constructed in such a way asto provide guidance by using the position of a sign included in data,the navigation device can make a preparation for guidance in advance toadjust the time that the navigation device provides the guidance.

Further, because the navigation device is constructed in such a way asto detect the position of a sign by using the camera and provideguidance, the navigation device can provide guidance by using the actualposition of a sign, thereby being able to solve the problem that thestored data are updated as time goes by, but cannot be used.

In addition, because the navigation device is constructed in such a wayas to store a rule governing where a sign is placed (e.g. how manymeters from a branch the sign is located) and provides guidance on thebranch with reference to the position of the sign, the navigation devicecan get to know a positional relationship between the current positionand the distance to the branch which is a target for guidance in advanceto specify the sign associated with the branch which is a target forguidance, and can provide the user with appropriate sign informationassociated with the branch.

Embodiment 13.

A navigation device in accordance with Embodiment 13 of the presentinvention is constructed in such a way as to provide guidance on ahighway exit or a road toward which a vehicle can move when making alane change from an HOV lane to a normal lane.

The structure of the navigation device in accordance with thisEmbodiment 13 is the same as that of the navigation device in accordancewith Embodiment 1 shown in FIGS. 1 and 2.

FIG. 19 is a flow chart showing an operation of the navigation device inaccordance with Embodiment 13, focusing on a guiding process. Hereafter,steps in each of which the same process in a corresponding step shown inthe flow chart of FIG. 16 is carried out are designated by the samereference characters as those shown in FIG. 16, and the explanation ofthe steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). A routesearch is then carried out (step ST3 c). The process of this step ST3 cis skipped at the time of providing no route guidance. It is thenchecked to see whether or not the vehicle is traveling in an HOV lane(step ST4 g). When it is determined in this step ST4 g that the vehicleis not traveling in an HOV lane, the navigation device ends the guidingprocess.

In contrast, when it is determined in step ST4 g that the vehicle istraveling in an HOV lane, the position of a lane changing permittedsection in which the vehicle is permitted to make a lane change from theHOV lane to a normal lane is then acquired (step ST5 l).

Then, when the vehicle moves to a normal lane at the position of thelane changing permitted section, either the name of a highway exit viawhich the vehicle can exit the highway (normal lane) or the road name ofa road existing ahead of the highway exit is acquired (step ST6 l). As amethod of acquiring the highway exit name or the road name used in thisstep ST6 l, a method of acquiring the highway exit name or the road namefrom information stored in a map data storage unit 16 (processing andstoring information from attributes or the like), a method of detectingthe information written on an actual sign by using a forwardly-existingsign detecting camera 15, or a software-based method of forwardlytracing links by using software to acquire the highway exit name or theroad name can be used. The details of this software-based method will bementioned later.

Then, guidance on toward which highway exit or road the vehicle cantravel after exiting the lane changing permitted section is provided(step ST7 l). More specifically, guidance on the name of a highway exitor the road name of a road existing ahead of the highway exit which isacquired in step ST6 l is provided. As this guidance, at least one ofvoice guidance, a telop, a telop and a beep (Pi sound), a guide mapdisplay, and so on is provided. After that, the navigation device endsthe guiding process.

Next, an example of the software-based method will be explained indetail. FIG. 20 shows a case in which a lane changing permitted sectionin which the vehicle is permitted to make a lane change between an HOVlane and a normal lane exists ahead of the vehicle, and a highway exitextending from a normal lane exists ahead of the lane changing permittedsection, and FIG. 20(a) shows a road image of the case and FIG. 20(b)shows a link image of the case which is expressed on map data.

FIG. 21 shows a status in which destination sign information is storedas interlink information. This example shows that the followingcharacters: “I-405 S Long Beach” are displayed on an actual destinationsign associated with a direction of travel from a link 3 to a link 4,and the following characters: “EXIT 13 Main Street Los Angeles” aredisplayed on an actual destination sign associated with a direction oftravel from the link 3 to a link 5.

When finding out a link 2, in which the vehicle can make a change lane,in a forward direction when the vehicle is traveling in an HOV lane, thecontrol part 30 traces the links in a forward direction of the vehicleto search for a highway exit link (or a highway branch link). In thisexample, the control part 30 can find out the highway exit link 5 andacquire the information on the highway exit from the interlinkinformation on the link 3 and the link 5 to provide the followingcharacters: “EXIT 13 Main Street Los Angeles.” When the vehicle getsclose to the section corresponding to the link 2, the control part 30displays the following characters: “EXIT 13 Main Street Los Angeles”acquired previously on the screen of a display unit 17, and, when thevehicle moves from the HOV lane to a normal lane in the lane changingpermitted section, the control part 30 provides guidance indicating thatthe user can use “Exit 13” to travel “Main Street” and then travel inthe direction of “Los Angeles.”

As a result, the user is enabled to determine whether the user shouldexit the HOV lane in either this lane changing permitted section or thenext lane changing permitted section.

By further incorporating the following conditions (1) to (3) into theabove search, the navigation device can provide more user-friendlyguidance.

-   (1) Set the distance of a section within which the control part    searches for the link 5 to be constant-   (2) Search for a plurality of exits-   (3) The link 5 is located at a fixed distance from the link 2    Although exit information is used as a restriction between links in    the above-mentioned example, exit information can be alternatively    stored in a node or a link.

As previously explained, the navigation device in accordance withEmbodiment 13 of the present invention can provide guidance on in whichlane changing permitted section the user should exit an HOV lane inorder to make it possible for the vehicle to reach the user'sdestination when the vehicle is traveling in the HOV lane, and enablesthe user to use the HOV lane throughout all of a section appropriate forthe user. Further, the navigation device can prevent the user fromovershooting the user's desired exit (traveling in the HOV lane over adistance longer than necessary) and then taking a circuitous route tothe destination, and can also prevent the user from making a needlesslane change from the HOV lane to a normal lane at an early time and thenrunning into a traffic jam.

Further, a criterion by which to determine whether or not to output atleast one of a voice of a street name, a telop, a Pi sound, or a guidemap as guidance on an exit at a time when the user exits an HOV lane canbe processed and incorporated into data, and guidance can be provided byusing the data. By registering linking of information showing which oneof lane changing permitted sections in each of which the vehicle ispermitted to make a lane change between an HOV lane and a normal lane isappropriate for entering each exit to this exit into the map data, anadjustment of a guidance time can be achieved in advance.

Further, by detecting a sign by using a camera and using the signdetected as the above-mentioned determination criterion, guidance can beprovided. By detecting linking of information showing which one of lanechanging permitted sections in each of which the vehicle is permitted tomake a lane change between an HOV lane and a normal lane is appropriatefor entering each exit to this exit from an actual road (using a camera)in software, guidance can be provided at an actual time, so thatreliable guidance can be provided for the user.

Further, by forwardly tracing links to detect an exit as theabove-mentioned determination criterion, guidance can be provided. Byforwardly tracing links by using software to provide linking ofinformation showing which one of lane changing permitted sections ineach of which the vehicle is permitted to make a lane change between anHOV lane and a normal lane is appropriate for entering each exit to thisexit, the navigation device can determine to which exit the vehicle canenter to provide guidance.

Embodiment 14.

A navigation device in accordance with Embodiment 14 of the presentinvention is constructed in such a way as to enable the user to seteither whether the user has exited an HOV lane or entered an HOV lane tothe navigation device in the structure of the navigation device inaccordance with Embodiment 1. The structure of the navigation device inaccordance with this Embodiment 14 is the same as that of the navigationdevice in accordance with Embodiment 1 shown in FIGS. 1 and 2.

FIG. 22 is a flow chart showing an operation when the user exits an HOVlane of the navigation device in accordance with Embodiment 14, focusingon a guiding process. Hereafter, steps in each of which the same processin a corresponding step shown in the flow chart of FIG. 15 is carriedout are designated by the same reference characters as those shown inFIG. 15, and the explanation of the steps will be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). It isthen checked to see whether or not a vehicle is traveling in an HOV lane(step ST4 g). When it is determined in this step ST4 g that the vehicleis not traveling in an HOV lane, the navigation device ends the guidingprocess. In contrast, when it is determined in step ST4 g that thevehicle is traveling in an HOV lane, it is then checked to see whetherthere exists a lane changing permitted section in which the vehicle ispermitted to make a lane change between the HOV lane and a normal laneahead of the vehicle (step ST5 m). When it is determined in this stepST5 m that there exists no lane changing permitted section in which thevehicle is permitted to make a lane change between the HOV lane and anormal lane ahead of the vehicle, the navigation device ends the guidingprocess.

In contrast, when it is determined in step ST5 m that there exists nolane changing permitted section in which the vehicle is permitted tomake a lane change between the HOV lane and a normal lane ahead of thevehicle, it is then checked to see whether the vehicle has entered thelane changing permitted section (step ST6 m). When it is determined inthis step ST6 m that the vehicle has not entered the lane changingpermitted section, the navigation device enters a standby state in whichthe navigation device repeatedly carries out the process of step ST6 m.When it is determined that the vehicle has entered the lane changingpermitted section in the standby state in which the navigation devicerepeatedly carries out the process of step ST6 m, the navigation deviceprovides guidance on exit from the HOV lane (step ST7 m). In this case,for example, the navigation device provides guidance indicating “Now isthe best time to exit the HOV lane.”

Guidance indicating an inquiry about whether the user has exited the HOVlane is then provided (step ST8 m). More specifically, a guidance timeadjusting unit 39 adjusts a guidance time when the navigation deviceprovides the guidance from pieces of HOV lane related informationacquired from an HOV lane determining unit 35 and an HOV lane entranceand exit extracting unit 36, and, when determining that the guidancetime has come, sends guidance time data to a display processing unit 40and to a voice message generating unit 41. The display processing unit40 generates display data for displaying information indicating “Haveyou exited the HOV lane?” according to the guidance time data sentthereto from the guidance time adjusting unit 39 and sends the displaydata to a display control unit 24 disposed in a control unit 19. As aresult, a guide map display or a telop display showing “Have you exitedthe HOV lane?” is shown on a display unit 17.

Further, the voice message generating unit 41 generates a voice messagefor providing the following information “Have you exited the HOV lane?”according to the guidance time data sent thereto from the guidance timeadjusting unit 39, and sends the voice message to a voice guidance unit42 as voice data. The voice guidance unit 42 converts the voice datasent thereto from the voice message generating unit 41 into a voicesignal, and sends this voice signal to a sound output unit 18. As aresult, voice guidance corresponding to the following voice message“Have you exited the HOV lane?” is outputted from the sound output unit18.

It is then checked to see whether a setting showing that the user hasexited the HOV lane has been made (step ST9 m). More specifically, whenreceiving an operation signal sent thereto from an input unit 11, acontrol part 30 of the control unit 19 checks to see whether thisoperation signal shows that a setting showing that the user has exitedthe HOV has been made. When it is determined in this step ST9 m that nosetting showing that the user has exited the HOV has been made, thenavigation device returns the sequence to step ST5 m and then repeatedlycarries out the above-mentioned processes. In contrast, when it isdetermined in step ST9 m that a setting showing that the user has exitedthe HOV has been made, the navigation device ends the guiding process.The guidance indicating “Have you exited the HOV lane?” can be providedby using at least one of a guide map display, a telop display, and voiceguidance. After the user makes a setting showing that the user hasexited the HOV lane after the control part 30 has provided the guidanceon exit from the HOV lane in this way, the control part prevents theguidance on exit from the HOV from being repeatedly provided after that.

FIG. 23 is a flow chart showing an operation at a time when the vehicleenters an HOV lane of the navigation device in accordance withEmbodiment 14, focusing on a guiding process. Hereafter, steps in eachof which the same process in a corresponding step shown in the flowchart of FIG. 12 is carried out are designated by the same referencecharacters as those shown in FIG. 12, and the explanation of the stepswill be simplified.

When the guiding process is started, map data are acquired first (stepST1). Vehicle position information is then acquired (step ST2). It isthen checked to see whether or not the vehicle is traveling in a normallane of a road in which an HOV lane is running parallel with the normallane (step ST4 e). When it is determined in this step ST4 e that thevehicle is not traveling in a normal lane of the road in which an HOVlane is running parallel with the normal lane, the navigation deviceends the guiding process. In contrast, when it is determined in step ST4e that the vehicle is traveling in a normal lane of the road in which anHOV lane is running parallel with the normal lane, it is then checked tosee whether there exists a lane changing permitted section in which thevehicle is permitted to make a lane change between a normal lane and theHOV lane ahead of the vehicle (step ST5 n). When it is determined inthis step ST5 n that there exists no lane changing permitted section inwhich the vehicle is permitted to make a lane change between a normallane and the HOV lane ahead of the vehicle, the navigation device endsthe guiding process.

In contrast, when it is determined in step ST5 n that there exists alane changing permitted section in which the vehicle is permitted tomake a lane change between a normal lane and the HOV lane ahead of thevehicle, it is then checked to see whether the vehicle has entered thelane changing permitted section (step ST6 n). When it is determined inthis step ST6 n that the vehicle has not entered the lane changingpermitted section, the navigation enters a standby state in which thenavigation repeatedly carries out the process of step ST6 n. When it isdetermined that the vehicle has entered the lane changing permittedsection in the standby state in which the navigation device repeatedlycarries out the process of step ST6 n, the navigation device providesguidance on entrance into the HOV lane (step ST7 n). In this case, forexample, the navigation device provides guidance indicating “Now is thebest time to enter the HOV lane.”

Guidance indicating an inquiry about whether the user has entered theHOV lane is then provided (step ST8 n). More specifically, the guidancetime adjusting unit 39 adjusts a guidance time when the navigationdevice provides the guidance from the pieces of HOV lane relatedinformation acquired from the HOV lane determining unit 35 and the HOVlane entrance and exit extracting unit 36, and, when determining thatthe guidance time has come, sends guidance time data to the displayprocessing unit 40 and to the voice message generating unit 41. Thedisplay processing unit 40 generates display data for displayinginformation indicating “Have you entered the HOV lane?” according to theguidance time data sent thereto from the guidance time adjusting unit 39and sends the display data to the display control unit 24 disposed inthe control unit 19. As a result, a guide map display or a telop displayshowing “Have you entered the HOV lane?” is shown on the display unit17.

Further, the voice message generating unit 41 generates a voice messagefor providing the following information “Have you entered the HOV lane?”according to the guidance time data sent thereto from the guidance timeadjusting unit 39, and sends the voice message to the voice guidanceunit 42 as voice data. The voice guidance unit 42 converts the voicedata sent thereto from the voice message generating unit 41 into a voicesignal, and sends this voice signal to the sound output unit 18. As aresult, voice guidance corresponding to the following voice message“Have you entered the HOV lane?” is outputted from the sound output unit18.

It is then checked to see whether a setting showing that the user hasentered the HOV has been made (step ST9 n). More specifically, whenreceiving an operation signal sent thereto from the input unit 11, thecontrol part 30 of the control unit 19 checks to see whether thisoperation signal shows that a setting showing that the user has enteredthe HOV lane has been made. When it is determined in this step ST9 nthat no setting showing that the user has entered the HOV lane has beenmade, the navigation device returns the sequence to step ST5 n and thenrepeatedly carries out the above-mentioned processes. In contrast, whenit is determined in step ST9 n that a setting showing that the user hasentered the HOV lane has been made, the navigation device ends theguiding process. The guidance indicating “Have you entered the HOVlane'?” can be provided by using at least one of a guide map display, atelop display, and voice guidance. After the user makes a settingshowing that the user has entered an HOV lane after the control part 30has provided the guidance on entrance into the HOV lane in this way, thecontrol part prevents the guidance on entrance into the HOV lane frombeing repeatedly provided after that.

As previously explained, in the navigation device in accordance withEmbodiment 14 of the present invention, when the user has made a settingshowing that the user has completed exit from or entrance into an HOVlane after the navigation device provide guidance on exit from orentrance into the HOV lane, the control part prevents the guidance onexit from or entrance into the HOV lane from being repeatedly providedafter that. More specifically, when the vehicle reaches a lane changingpermitted section while traveling in an HOV lane, the navigation deviceprovide guidance on exit from the HOV lane, and, when the user makes asetting showing that the user has exited the HOV lane according to thisguidance, the control part prevents not only the guidance on exit fromthe HOV lane but also guidance on entrance into the HOV lane from beingprovided. When the vehicle reaches a lane changing permitted sectionwhile traveling in a normal lane running parallel with an HOV lane, thenavigation device provides guidance on entrance into the HOV lane, and,when the user makes a setting showing that the user has entered the HOVlane according to this guidance, the control part prevents not only theguidance on entrance into the HOV lane but also guidance on exit fromthe HOV lane from being provided. Thus, immediately after the user hasexited or entered an HOV lane, the navigation device can prevent anyunnecessary guidance from being repeatedly provided.

Further, in above-mentioned Embodiment 14, because guidance forinquiring whether the user has made a lane change is provided by using,for example, a telop display or the like, the navigation device canprevent meaningless guidance from being provided after the user inputsinformation showing that the user has exited an HOV lane in response tothis guidance.

A navigation device can also be implemented by combining all ofabove-mentioned Embodiments 1 to 14. Further, all the numerical valuesincluding distances used in above-mentioned Embodiments 1 to 14 areexamples, and can be changed to arbitrary values.

INDUSTRIAL APPLICABILITY

The present invention can be used for a vehicle-mounted navigationdevice which is requested to provide guidance for assisting a lanechange between an HOV lane and a normal lane.

The invention claimed is:
 1. A navigation device comprising: a memorydevice that holds a computer program; an output device comprising atleast one of a display and a speaker; and a processor that executes thecomputer program read out from the memory device, wherein the computerprogram describes a process of: acquiring map data in which a singlelink represents a plurality of lanes of a road including at least onespecial lane and a plurality of not nal lanes, the map data being a mapdata in which entrance and exit between a particular special lane of theat least one special lane and one of the normal lanes which is adjacentto the particular special lane are permitted only in a predeterminedlane-changing permitted section; extracting an entrance and exit sectionof the road which exists ahead of a vehicle and in which the vehicle ispermitted to make a lane change between the particular special lane andthe adjacent normal lane on a basis of the acquired map data andposition information about the vehicle; extracting a branch point on theat least one special lane which exists ahead of the vehicle on a basisof the acquired map data and the position information about the vehicle;determining a guidance time as a future point in time in such a way thatthe guidance time varies depending on whether a length of saidlane-changing permitted section is shorter than a predetermined lengthor greater than the predetermined length; and when the determinedguidance time occurs, displaying or audibly outputting by said outputdevice exit guidance notifying that the vehicle is permitted to exit theparticular special lane onto the adjacent normal lane or entranceguidance notifying that the vehicle is permitted to enter the speciallane from the adjacent normal lane, or branch guidance on the branchpoint on the special lane, such that the provision of the guidance doesnot begin until the determined guidance time.
 2. The navigation deviceaccording to claim 1, wherein the process executed by the processorfurther includes searching for a route leading to a destination,determining the guidance time with reference to an exit or a branch of ahighway on the route which is searched for and providing the exitguidance at the determined guidance time.
 3. The navigation deviceaccording to claim 1, wherein the process executed by the processorfurther includes searching for a route leading to a destination, anddetermining the guidance time with reference to a highway entrance startpoint on the route which is searched for and providing the entranceguidance at the determined guidance time.
 4. The navigation deviceaccording to claim 1, wherein the process executed by the processorfurther includes, when the lane changing permitted section has thepredetermined length or greater, preventing at least one of the exitguidance and the entrance guidance from being provided.
 5. Thenavigation device according to claim 4, wherein the process executed bythe processor further includes preventing at least one of the exitguidance and the entrance guidance from being provided in accordancewith an user's setup.
 6. The navigation device according to claim 1,wherein the process executed by the processor further includes, afterproviding either the exit guidance or the entrance guidance, preventingthe exit guidance or the entrance guidance from being repeatedlyprovided after that when a user makes a setting showing that the userhas completed exit or entrance.